Problem 100 - Objective Biology for NEET

Question

Stele is made up of (in dicot root) (a) Pericycle (b) Vascular bundle (c) Pith (d) All of these

Step-by-Step Solution

Answer

The correct answer is (d) All of these. This is because the Stele in the dicot root is made up of the pericycle, vascular bundle and the pith.

Step 1: Identification

First understand what Stele is. Stele refers to the central part of the root or stem containing the tissues derived from the procambium. These include the pericycle, vascular tissue (xylem and phloem) and pith (if present).

Step 2: Matching components to options

Evaluate each of the given options (Pericycle, Vascular bundle, and Pith) and see whether they form part of the Stele in dicot roots. All of these are parts of the stele.

Step 3: Choosing the correct Answer

Since the pericycle, vascular bundle and pith are all components of the stele in a dicot root, the correct answer is (d) All of these.

Key Concepts

Stele

The stele is an important concept in botany, especially when studying dicot root structures. Imagine the stele as the central cylinder of the root, akin to the core of a cable that houses different wires. In the case of a dicot root, the stele is the central part that contains tissues developed from the procambium. These tissues comprise the pericycle, vascular bundles (xylem and phloem), and sometimes the pith.

Being at the heart of the root, the stele plays a critical role in the conduction of water and nutrients. It provides structural support and is essential for growth. In essence, the stele is like a backbone, giving stability and functionality to the root system. Understanding what makes up the stele gives insight into how plants transport vital resources from the root to other parts.

Pericycle

The pericycle is a layer of cells found within the stele, just inside the root's endodermis. Think of it as a thin protective coat that wraps around the inner core of the root. This layer is incredibly important for a plant's development.

• The pericycle is responsible for giving rise to lateral roots, aiding in increased absorption of water and nutrients from the soil.
• It also plays a crucial role in the plant's secondary growth, contributing cells to the vascular cambium.

By understanding the function of the pericycle, we can appreciate how plants adapt and thrive in different environments, continually expanding their root systems to meet their needs.

Vascular Bundle

The vascular bundle in dicot roots is a part of the stele composed of two main types of tissue: xylem and phloem. Think of xylem as a water pipe. It transports water and dissolved minerals from the roots upwards to the rest of the plant.

• Xylem tissues in dicot roots typically form a cross shape in the center, maximizing support and efficient transport.
• Phloem, on the other hand, is responsible for transporting the sugars produced by photosynthesis from the leaves to other parts of the plant including the roots.
  

Together, xylem and phloem make up the vascular bundle, acting like a highway in the plant, enabling the transfer of essential nutrients and sustenance throughout the plant structure.

Pith

Within the stele, the pith is sometimes present, mostly in stems rather than in all dicot roots. The pith is a central part of the stele, responsible for storage and transport of nutrients.

• The pith consists mostly of parenchyma cells, which are involved in storage and can help in the transport of nutrients and metabolites across the root.
• Its presence can indicate the plant's ability to store more nutrients and contribute to the overall structural integrity of the root.

When learning about roots, the presence or absence of the pith enhances our understanding of how different plants utilize their root structures for survival and efficiency across various environments.